Such sub-assemblies are frequently also referred to as rotor and stator. In these sub-assemblies, electrical signals are converted into optical signals and are supplied contactlessly via an air path to a photodetector, where they are converted into electrical signals again. Devices of this type are used in many technical fields for transmitting electrical signals from a stationary unit to a rotating electrical unit.
German Patent No. 44 28 790 describes a device for the bidirectional transmission of information, in which photoelectric receivers and transmitters are disposed eccentrically in relation to the axis of rotation.